Piston and cylinder arrangements are used in a variety of mechanical devices, such as valves and pressure regulators, for example. O-rings are commonly used to form a seal between an outer wall of the piston and an interior wall of the cylinder, in which the piston is supported for slidable movement relative to the cylinder. The O-rings are typically received within an annular groove of the outer wall of the piston, and slide against the interior wall of the cylinder during movement of the piston relative to the cylinder.
A lubricant, such as grease, is generally coated on the O-rings and the walls of the cylinder and piston to reduce friction between the interior wall of the cylinder and the O-ring. This extends the life of the O-ring and, thus, the operational life of the mechanical device, in which the O-ring is being used.
The amount of lubricant available to lubricate the O-ring is generally reduced over time due to use of the mechanical device. As a result, it is necessary to periodically replenish the lubricant. This generally involves disassembling the mechanical device and applying a new coating of lubricant to the O-rings and the walls of the piston and cylinder.